Pharmaceutical products, as for instance tablets, capsules, pills, suppositories, dragées etc. are typically packed in bottles, bags, blisters, folding boxes and similar containers. Blisters have a plastics sheet in which a plurality of deep-drawn cups is formed, each being filled with pills and being collectively sealed by a cover sheet. The filling of pills or tablets into the packages, particularly into blisters, is carried out by automatically operating machines, which are capable of inserting the respective products accurately and precisely at high speed. Conventional packaging machines include for this purpose several supply tubes and grooves which convey the pills or tablets from a reservoir in the direction towards their receptacles. A precise alignment and introduction of pills may be critical, particularly for pills being inserted into the cups of a blister.
When supplying the pills through supply tubes in which they fall downwards caused by the effect of gravity, the pills might get stuck if, caused by the required dosage conditions, the pills come to a stop and partially overlap so that they stand up obliquely. One therefore speaks of a “shingling” of the pills.
US 2004/0035878, incorporated herein by reference in its entirety, discloses a supply tube that reduces the above-mentioned shingling. The supply tube has a helically extending channel that extends between the inlet end and the outlet end of the tube. This helical channel has a substantially rectangular cross-section that is larger than the cross-section of the pills to be conveyed. “Substantially rectangular” in this case means a cross-section where the largest extension of a first side of the rectangle in a first direction is larger than the largest extension of a second side in a second direction perpendicular to the first direction but where both sides do not necessarily have to be straight but may also be adapted to the cross-sectional shape of the tablets, pills and similar products to be conveyed through. This definition also applies to the present invention. When the pills fall through the above-cited helical channel, the pills perform a rotation due to the shape of the channel, but they do not rotate with respect to the channel. Within the channel the pills have a limited mobility with respect to the channel walls. This mobility reduces or prevents the jamming of the pills in the channel caused by shingling.
Relatively complex tools and molds are required for manufacturing a supply tube of the above-mentioned kind. It is an object of the present invention to provide a supply tube that prevents jamming of the products conveyed therein as a result of shingling and which can be manufactured in a simple manner.